An Updated Report on Corona Viruses

Corona viruses are old viruses which are divided into three groups. Groups one and three viruses induce disease in animals, and human viruses such as MERS and SARS are in group two.

This study was performed using international scientific sources and new researches findings.

Corona viruses are in the form of tiny spherical particles, and genome of the virus, which contain a single-stranded RNA, it causes changing in pathogenesis and severity of the virus and its sensitivity to antiviral antibodies. Attaching the virus to the cell is the first step in affecting a host. This is very important step and determines the tropism and the onset of viral infection. After virus binds to the cell by S protein, it fuses to the cell membrane and release the viral RNA genome inside the host cell cytoplasm. Human coronaviruses enter and grow in the epithelial cells of the upper respiratory system, and also alveoli and the lower respiratory system. But in COVID-19, it is not obvious the organs which virus penetrates and grows. The best diagnostic test is RT-PCR, but sometimes report false-negative results. It is very useful if this test used with clinical symptoms and radiological images. Serological methods have been used for some coronavirus and SARS viruses. One of the serological methods is testing serum level of IgG and it is useful in determining the asymptomatic infection or exposure to virus. The exact date of the virus's appearance is not known, but seems it existed some time before December 2019, or that it was not tested or reported.

Physiopathology of the virus, involved cells and tissues, established level of immunity and the pathogenesis mechanism and future random mutations of the virus are not fully understood. It is hoped many of these issues will become clear in the future.